1. Field of the Invention
The present invention relates to an earthquake damage spread reducing method and an earthquake damage spread reducing system for use in a semiconductor manufacturing apparatus.
2. Background Art
The manufacture of semiconductor devices includes steps of providing various processes, such as oxidation, film forming, and the like, to each semiconductor wafer to be processed. As the apparatus for carrying out such processes, for example, a semiconductor manufacturing apparatus (also referred to as a vertical-type heating apparatus) is currently employed, which enables batch-type processes for multiple sheets of wafers (e.g., see Patent Document No. 1). The semiconductor manufacturing apparatus includes a loading area (or transfer area) below a vertical-type heating furnace having a furnace port at its bottom portion. In the loading area, a lifting mechanism, a loading mechanism, and the like are provided. The lifting mechanism is configured to carry in and carry out a boat relative to the heating furnace by raising and lowering a cover for opening and closing the furnace opening, while the boat is placed on a top portion of the cover via a heat insulating mould. In the boat, multiple sheets (about 100 to 150 sheets) of wafers each having a relatively large size, for example, a 300 mm diameter, are loaded. The loading mechanism is adapted to transfer the wafers between the boat and a carrier (or wafer storing container) in which the multiple sheets of wafers are stored.
As the semiconductor manufacturing apparatus, those employing the so-called two-boat system have been proposed, in each of which two boats are employed, whereby while the one boat is being loaded on the cover and carried into the heating furnace so as to be subjected to a heating process, the other boat can be used for changing processed semiconductor wafers with new ones.
The boat is made from quartz, which is quite expensive. The wafers are also expensive, thus the production cost will increase as the processing steps advance. Accordingly, handling of these components or materials must be carried out with greater care.
Patent Document 1: TOKUKAI No. JP2000-150400, KOHO
However, in the batch-type semiconductor manufacturing apparatus described above, the construction of the apparatus poses various restrictions on the conditions for the software and hardware, as such making it difficult to render the apparatus better suited for an earthquake resistant construction or earthquake-proof function, thus being currently insufficient against earthquake problems. Therefore, when an earthquake occurs and the apparatus experiences a greater shake, fall down and destruction of the boat, falling off from the boat of wafers and their breakage, and leakage of a gas may tend to be caused. In addition, if such damage occurs, it should take a longer time to make the apparatus recover for restart of the manufacture. Therefore, a greater earthquake would lead to more serious damage.
The present invention was made in light of the above circumstances, and it is therefore an object thereof to provide an earthquake damage spread reducing method and an earthquake damage spread reducing system for use in a semiconductor manufacturing apparatus, which method and system can predict occurrence of an earthquake in order to prevent fall down and destruction of the boat, minimize the damage and thus reduce the time required for recovery of the apparatus.